The only river on the planet which flows in both the northern and southern hemispheres.

The Congo actually emerges from the Lualaba River which rises from a plateau some 1,418 metres above sea level.  The Lualaba joins with the Lufira and the Luvua Rivers.  The Luvua is dervived from the Luapula (also known as the Chambezi) which is also considered to be a headstream of the Congo.  Many dramatic waterfalls exist along the Luvua and the commbined rivers are joined by the Lukuga which flows in from Lake Tanganyika.  At 80 km downstream, a long navigable section ends as the the "Portes d'Enfer", a particularly wild section of rapids, generates copious amounts of white water.  The rapids run for some 120 km, at which point another navigable section kicks in and lasts for another 300 km until it reaches the Stanley Falls.  After the seven sections of the Stanley, the river officially becomes the Zaire and is then navigable for 1600 km.  Lower down the river is as much as 15 km wide.  Navigability ends with the Stanley Pool, across which the cities of Kinshasa and Brazzaville face each other.  After the Pool comes the 32 sections of the Livingstone Falls as the river cuts through the Crystal Mountains.  It then broadens out into an estuary, part of which forms a large whirlpool known as the "Devil's Cauldron".  The river then splits into two channels around Matoba Island followed by the delta.  Beneath the surface, the river has carved a canyon which extends far out to sea.  

Tributaries

Lualaba, Luapula, Luvua, Lufira, Lukuga, Lomami, Aruwimi, Ubangi, Sangha, Lukenie, Kasai